I know. That's why I said that it would be at least 15 years before the Tribunal would officially declare the covenant dissolved.
With the last Tribunal meeting being in 1221, that means it's been between 19 and 26 years since the destruction of the covenant.
No, the island is not the actual covenant site, although some labs may be installed there eventually. The magi won't know about the island right away, as it is hidden from mundane sight.
If you look at the ruins on Google Maps here, you can see that the ruins are organized on a square area that seems slightly elevated from the surrounding terrain. All of that area has a +3 magical aura.
There are a number of buildings that will already be there (grog barracks, stables, seperate houses for 4 magi including space for a lab, a dozen or so smaller houses for covenfolk and specialists). Those buildings are in disrepair, since they've been abandonned for 20-ish years. There is plenty of space there to build more. Amongst the ruins, there is the entrance to a network of caves where the aura is stronger. Some labs can be set up in those caves also, although it seems nothing of the sort had been done originally.
Looking at this larger map of the area, you can see Tanais at the center top and Azov at the bottom on the other side of the delta. The magical aura weakens as it extends from the covenant. Upland it is +2 for about 1 mile north and 2 miles west and east. South into the delta, it is much larger, with most of the delta covered by a +1 magical aura.
The closest village are on each side of the covenant about 5 miles west (what is identified as Morskoy Chulek on the map). That's where the large ship(s) bringing the magi can land, as the channel into the delta is too narrow and shallow for large ships. Fishing boats and barges can navigate it, though. There is also another village to the east about 7 miles away (what is identified as Kalinin on the map). Azov is the big city, on the other side of the delta. A lot of trade goes through there.
The Sea of Azov ices over during the winter, so travel by ship becomes impossible. Crossing the delta over the ice is dangerous but not impossible, as the thickness varies a lot. Water level is also quite high during spring, making navigation more dangerous but certainly possible.